public class Main {

    public static void main(String[] args) {
        Solution solution = new Solution();
//        int result = solution.lengthOfLongestSubstring("pwwkew");
        int result = solution.lengthOfLongestSubstring("abcabcbb");
//        int result = solution.lengthOfLongestSubstring("aa");
//        int result = solution.lengthOfLongestSubstring("ab");
//        int result = solution.lengthOfLongestSubstring("");
        System.out.println(result);
    }

}